Replacing cast-iron elbow

I'm a good DIY'er with a good set of tools, but I have never worked with cast iron before. Since this is a small, localized problem it seems like a good place to start.

The drain in my seldom-used bathtub has developed slow drip at a rust spot in a 45-degree cast-iron elbow. The 2-inch pipe on either side of the elbow appears to be in good condition, although I can't be certain until I remove the elbow.

I fear that this will become a nightmare, too, which means that I want to do the minimum possible work. My greatest fear is that cutting out the elbow with a sawsall will generate so much vibration that it will cause leaks/crack in the pipes I'm cutting away from. Do you think I would reduce this danger by cutting out the elbow manually with a hack saw?

As the long view photo reveals, I'll have the choice of cutting the bottom close to the elbow, or cutting it down near the 90-degree joint. I favor the latter, as it will give me more slop to play with when I start assembling the ABS replacement.

You drill the lead out of the fitting with a power drill, clean the fitting and fit it with a no-hub adapter. Expect to go through a broken bit or two.

Has been may years since I drove a tiger, belonged to a club that had one. The tail always looked too close for some reason. It was always fun to tool around in.

Paul

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I have room to try drilling at the bottom end, but the top end is too close to the floor. I've also bought some the recommended recip-saw bits and have rented a snap cutter. IOW, I've got this thing surrounded.

BTW, I've used TigerDriver on dozens of forums and you're the first person ever to know what it means. Have a look: www.tinyurl.com/2hy9k

I cant get either page to load but from all I've read I'd just snap it on either side of the hubs and eliminate them altogether...if there's enough room and the the cast iron piping itself isnt deteriorated to the point of crumbling. I'd then just transition from the cast iron to pvc or abs with no hub couplings. I've drilled out lead and while there's nothing at all wrong with doing it that way I just find it to be faster and simpler for me to snap it.

MY opinion is that there is nothing wrong with the pipe. It appears to be the residue from a tiny leak in the lead joint. I would just seal the lead more tightly with a hammer and blunt chisel, or caulking iron if you happen to have one. Then wire brush the rust off. You have a similar appearance at the elbow down at the Y connection. If I were doing it, I would try to find a different point to connect that drain into the system, maybe into the ABS pipe visible in the background, to avoid that sharp 135 degree turn at the bottom.

MY opinion is that there is nothing wrong with the pipe. It appears to be the residue from a tiny leak in the lead joint. I would just seal the lead more tightly with a hammer and blunt chisel, or caulking iron if you happen to have one. Then wire brush the rust off. You have a similar appearance at the elbow down at the Y connection. If I were doing it, I would try to find a different point to connect that drain into the system, maybe into the ABS pipe visible in the background, to avoid that sharp 135 degree turn at the bottom.

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Although it isn't visible in the photo, the side of the upper elbow is scaling away from rust and theres a 2mm hole all the way through.

This is all moot, anyway, as I cut out the offending section yesterday--from the top of the 45-degree elbow, to the T at the bottom. I made the upper cut flush with the top of the elbow, which leaves me with about 2.5" of pipe to connect a clamp fitting to; at the bottom end, I left about 4" above the T.

The interesting thing is that I made both cuts using my recip saw and a single blade (BLU-MOL 6" 14tpi from Home Depot). To avoid vibration, I used the fastest speed possible while applying light downward pressure. It took me about 10 minutes to make both cuts and another couple of minutes to dress up the pipe edges with a grinder.

So now it's on to replacing with ABS. I'm going back to Home Depot tomorrow, which has a huge selection fo PVC/ABS, but, of course, nobody around who knows a thing about it.

(1) What's the name of the elbow I'm going to need? It needs to connect the 2.5" stub of cast iron at the top to a run of straight ABS pipe .

(2) What's the name of the flexible union that joins the ABS run to the cast-iron stub below? Or do I just buy a length of the flexible material, cut it to length, then clamp it on? If so, what is the flexible material?

(3) Is ABS joined in the same manner as PVC; that is, a primer and a solvent-glue? If so, can I use the PVC chemicals I have on hand?

You need either a street 1/8 bend or a regular one, depending on how the pipe fits up to the fitting. Then two No-hub couplings because HD will probably not have sch 40 plastic to cast iron bands, which are almost the same size anyway. You use black ABS cement without a primer. PVC cement does not work.

I took the elbow and attached length of pipe to a local plumbing suppy, plopped it on the counter, and ask for the suitable ABS replacements. I was given an 60-degree ABS elbow, a length of ABS pipe, and two Fernco couplings. One coupling connected the pipe to the lower stub.

At the top, I cemented a 2" piece of the ABS pipe into one end of the elbow, then cemented the other end of the elbow to the pipe. I then attached the elbow assembly to the top CI stub with the other no-hub coupling. After five minutes to let the cement cure, I torqued all clamps down hand-tight with a nut driver.

I then filled the tub and let 'er rip. Not a drop! I attribute this to beginner's luck.

use a 4" grinder with a zip cutter and cut out above the fitting and along the straight section, use 2 ferncos and a section of new ci or plastic. snap cutter will fracture old cast like glass. good luck ps use safety glasses